Phosphoric Acid → 4,4-Dimethylthiochroman

HRID 2219796Notes

Reaction equation

HRID 2219796 reaction equation
[C:1]1([SH:7])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.Br[CH2:9][CH:10]=[C:11]([CH3:13])[CH3:12].[OH-].[Na+].O=P12OP3(OP(OP(O3)(O1)=O)(=O)O2)=O.P(=O)(O)(O)O>CC(C)=O.C1(C(SC(C2C=CC=CC=2)C=C(C)C)C=C(C)C)C=CC=CC=1.C1C=CC=CC=1>[CH3:12][C:11]1([CH3:13])[C:6]2[C:1](=[CH:2][CH:3]=[CH:4][CH:5]=2)[S:7][CH2:9][CH2:10]1

Participants

9

Reactant 5

HCID 1004Phosphoric AcidHCID 7969ThiophenolHCID 14798Sodium HydroxideHCID 14812Phosphorus oxide (P4O10)HCID 700922-Butene, 1-bromo-3-methyl-

Product 1

HCID 110194304,4-Dimethylthiochroman

Reagents, catalysts & solvents 3

HCID 180AcetoneSolventHCID 241BenzeneSolventHCID 54518102Phenyl-3-methylbut-2-enylsulfideSolvent2×

Procedure

Thiophenol (1) and 1-bromo-3-methyl-2-butene (2) are heated at reflux with sodium hydroxide in acetone resulting in phenyl-3-methylbut-2-enylsulfide (3). The phenyl-3-methylbut-2-enyl sulfide (3) is cyclized by refluxing with phosphorus pentoxide and phosphoric acid in benzene to yield 4,4-dimethylthiochroman (4). The 4,4-dimethylthiochroman (4) is reacted with acetyl chloride catalyzed by tin (IV) chloride (SnCl4) in benzene resulting in 4,4-dimethyl-6-acetylthiochroman (5). The 4,4-dimethyl-6-acetylthiochroman (5) is dehydrated with lithium diisopropylamide (LDA) and diethyl chlorophosphate in tetrahydrofuran (THF) results in the initial 6-ethenyl phosphonate intermediate (6). This intermediate undergoes further reaction with two equivalents of LDA to give 4,4-dimethyl-6-ethynylthiochroman (II).

Sources & evidence

ORD record
ord-2ee8ebb1710f4ab6b75bce913bac7040
Source dataset
uspto-grants-2008_08
Patent number
US07414143B2

Reaction notes

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